Rock-drilling bits



June 1, 1965 B. P. WARBURTON ROCK-DRILLING BITS 2 Sheets-Sheet 1 Filed Aug. 1.- 1960 A B. P. WARBURTON ROCK-DRILLING BITS June 1, 1965 2 Sheets-Sheet 2 Filed Aug. 1. 1960 I United. States Pate H 3,186,501 ROCK-DRILLING BITS Bruce Percival Warburton, Market Overton, Rutland, England, assignor, by mesne assignments, to P. 8: V. (Mining 8; Engineering) Limited Filed Aug. 1, 1960, Ser. No. 46,807 Claims priority, application Great Britain, Aug. 28, 1959, 29,431; Oct. 5, 1959, 33,656 9 Claims. (Cl. 175-412) This invention relates to drilling bits for rigs for sinking oil, water or gas wells, blast holes, exploratory and test drilling of rock formations and like purposes, of the kind known in the art generally as Rock Bits, which may be of different types, such as DragBits which carry cutting blades, Diamond Bits, which have faces armed with diamonds or Roller Bits" which have downwardly extending arms rotatably supporting rollers, usually conical, armed with one or more rows of cutting teeth which exert a rolling and percussive action on the drilled formation.

.An object of the invention is a rock bit assembly in which drag or diamond bit blade arms or roller bit arms may be interchangeably fitted and worn out or damaged blade or roller bit arms can be easily and quickly replaced.

In this way expense is saved, since the replaceable blade arms or roller bit arms are cheaper and simpler to make than bits of unitary construction directly connectible to the drill pipe or drill collar.

A more particular object of the invention is a rock bit assembly comprising two or more similar detachable bit arms, terminating either in cutting blades, diamond-bear ing faces or rotatable toothed rollers, a hollow shank, a holder box securable to the drill pipe or drill collar and having a screw-threaded connection to said shank, said shank terminating downwardly in a ball-shaped enlargement engageable with complementary recesses in said arms, an internally tapered sleeve tightly engageable with a complementary external taper of said arms, and driving connection means between said shank and said sleeve.

In one form of the assembly, the driving connection takes the form of a splined joint between the shank and the tapered sleeve, the top of which abuts directly on the box; and in another found the, assembly, the shank has a screw-threaded connection with the tapered sleeve .of opposite hand to its screw-threaded connection with the box. The latter form of the assembly preferably includes a collar, in splined engagement with the shank, inserted between the lower edge of the box and the upper edge of the tapered sleeve. I

Preferably, the bit arms are rotationally keyed to the tapered sleeve, mainly for the purpose of locating the arms relatively to the tapered sleeve during assembly,

- the rotation being communicated to the arms when the assembly has been tightened up by friction between the female taper of the sleeve and the male taper of the arms.

The tapered sleeve may also havereaming stabilizers on its outer surface, which assist in guiding the bit; and these stabilizers may .have cutting edges attheir upper ends, which assist when taking the bit out of the hole, if the latter is obstructed by loose cuttings or pieces of the drilled formation lodged in the hole, if the bit is rotated while withdrawing it, thus causing the reaming stabilizers to exert a cutting and clearing action on such loose cuttings or pieces.v

How the foregoing objects, and such others as may hereinafter appear, are attained, and the nature of the invention; will be more fully understood from the following description with reference to the accompanying drawings of two embodiments of the invention, given by way of example only and without implied limitation of the ice scope of the invention, which is defined in the hereto appended claims.

In the drawings:

FIGURE 1 is an elevation, partly in axial section, of one embodiment of the invention;

FIGURE 2 isa similar view of a second embodiment;

FIGURE 3 is a section on the line IH-III of FIG- URE 2;

FIGURE 4 is a detail view in elevation viewed in the direction of arrow IV of FIGURE 2; and

FIGURE 5 is a fragmentary view corresponding to the lower part of FIGURE 2, showing roller bit arms replacing drag bit arms.

Referring to FIGURE 1, 10 is the hollow shank terminating in a ball-shaped enlargement 12 and having a lefthanded external screw-thread 14 (the sense of rotation of the bit being right-handed). 16 are the bit arms (which for convenience of reading the drawing are shown as being two in number) having downwardly and inwardly directed pins, terminating respectively in a spear-point 18 and a double chisel 20, and rotatably supporting rollers 22, each of which is armed with three rows of teeth 24. The arms have female spherical surfaces 26 which fit the ball 12, external tapers 28 which fit an internal taper 30 of a sleeve 32, and keyways 34 engaged by keys 36 on sleeve 32. The latter has an internal, left-hand screw-thread 38 engaging the screw-thread 14 of shank 10.

The upper end of shank 10 has an external, right-hand screw-thread 40 engaging an internal screw-thread 42 of the connecting box 44, which is connected to the drillcollar or drill-pipe in any convenient way. Between the screw-threads 14 and 40 the shank 10 has an externally splined portion 46 of enlarged diameter engaging internal splines 48 of a collar 50, which, when the bit is assembled as shown in the drawing, is held in position between the connecting box 44 and the tapered sleeve 32.

shank 10 sufficiently to extract the keys 36 from the key- Ways 34 and to enable the arms 16 to be disengaged from the ball 12 and so removed. I

Re-assembly is effected by performing the foregoin steps in reverse.

Referring now to FIGURES 2 to 4, in which elements common to these figures and to FIGURE 1 are identified by the similar reference characters, the second embodiment differs from the first (illustrated in FIGURE 1) mainly in that the screw-threaded connection 14, 38

between the shank 10 and tapered sleeve 32, and the collar 50 are omitted, the splined portion 46 of the shank 10 engaging complementary splines 48 formed, in this instance, in the tapered sleeve 32'.

In this embodiment, the lower end of the box 44 bears directly on the upper end of the tapered sleeve 32', and, when the box is screwed down the thread 40 of the shank 10,, it forces the internal taper 30 of sleeve 32' into tight frictional engagement with the external taper 28 of the arms 16, which are located by the ball 12 of'shank 10' and also by a flange 58 on the shank engaging complementary arcuate grooves formed in the bit arms 16'. It is to be noted that the hand of the screw-threads 40, 42 is the same as the direction of rotation of the assembly when drilling, so that the resistance encountered by the bit tends to tighten the tapers 30 of the sleeve 32 and 28 of the arms 16' on one another.

The arms 16 are shown as drag bit arms, three in number, having cutting blades 52 formed thereon.

The tapered sleeve 32' further has reaming stabilizers 54 formed on its outer surface, shaped as shown in FIG- URES 3, 4 and 5. In FIGURE 3 the direction of rotation is indicated by'an arrow, and FIGURE 4 shows the cutting edge 60 at the upper end of the stabilizer 54, the purpose of which has already been mentioned.

' The box 44 has an external taper screw-thread 56 for connecting it to the drill-pipe or drill-collar of the drilling rig.

Dismantling of the assembly is effected by unscrewing the box 44 from the shank the latter being held against rotation by holding the tapered sleeve 32 with a'wrench, the splined joint 46, 48 preventing the shank 10 from rotating. When the box 44 and shank 10' have been separated, the tapered sleeve 32 can be slidoif the shank 10 and arms 16 upwardly, thus releasing the arms 16' from the shank.

Reassembly is effected by reversing the foregoing procedure, rotation of the arms 16' relatively to the sleeve 32 being prevented during assembly by the keys and keyways 36, 34'. 1

FIGURE 5 shows the lower end of the assembly of FIGURES 2 to 5, in which the drag bit arms 16' of FIG- URES 2 to 5 have been replaced by arms 16' carrying roller bits 18, 22, 24 generally similar to those of FIG- URE 1. a

It will be understood that the invention is not limited to the details of the constructions illustrated in the drawings and described with reference thereto, but includes all such modifications and variants as are within the competence of those skilled in the art Without departing from the spirit and scope of the invention as defined in the appended claims. For instance, any number of bit arms, other than two or' three, may be used, but usually three or four will be most suitable.

Having thus described the invention, what is claimed as new and desired to be secured by Letters Patent is:

1. A rotary drill bit assembly comprising, in combination, a hollow shaft having an enlargement at its lower end and a threaded connection at its upper end, a connector piece attached to said threaded connection, said shaft carrying axially directed elements intermediate said ends, a collar surrounding the shaft, an upper region of the collar having elements complementary to said shaft elements and forming therewith peripheral engagement the bit arms to the collar, said connector piece bearing upon the upperregion of the collar to secure the assembly in position, the maximum dimension of the shaft enlargement then lying within the collar lower portion.

.2. A rotary drill bit according to claim 1 wherein a circumferential flange is. formed on the shaft between the enlargement and the axially directed elements, corresponding recesses being formed in the bit arms, said flange and recesses providing axial location means between said shaft and arms.

3. A rotary drill bit assembly comprising, in combination, a series of drill bit arms, each having an upper support region comprising an inner surface formed with a depressed region of increased radius and an upwardly tapering outer surface of frusto-conical segmental shape,

at least one outwardly projecting element being formed adjacent to the lower end of said segment outer surface, a hollow drill shank having an enlargement at its lower end upon which said depressed regions fit closely, a collar surrounding said arms having a lower portion inner surface which is of downwardly flaredfrusto-conical shape closely fitting said arm outer surfaces, slots in said collar inner surface receiving the outwardly I projecting elements, an upper portion of the collar extending above the bit arms to surround an intermediate region of the shank, peripheral engagement means between an upper portion of the collar and said intermediate region comprising complementary elements on said portion inner surface and said region outer surface preventing relative rotation between the collar and the shank, the shank being screwthreaded at its upper end and a connector piece for attachment of the assembly to a drilling rig engaging said thread being securable thereby to abut the collar and lock the bit arms in position.

4. A rotary drill bit assembly according to claim 3 wherein said bit arms depressed regions are located wholly within the length of said frusto-conical segmental surfaces.

5. A rotary drill bit assembly according toclaim 3 wherein a circumferential flange is formed on the shank between the enlargement and the circumferential engagement means, corresponding recesses being formed in the bit arms, said recesses being located above said outwardly projecting elements.

6. A rotary drill bit assembly according to claim 3 further comprising side reaming cutters which project outwardly from the outer peripheral surface of the collar.

7. A rotary drill bit assembly comprising, in combination, a hollow shank having a threaded connection at an upper end, a connector piecesecurable thereto for attachment of the assembly to a drill stern, a bulbous enlargement at the lower end of the shank, a collar surrounding the shank comprising a lower portion having a downwardly widening frusto-conical inner surface and an upper portion located intermediate the length of the shank, drivingconnection means being provided between the upper portion and the shank, a circumferential flange on said shank between the enlargement and said driving means, at least two similar detachable bit arms frictionally securable between the shank and the collar lower portion, said arms having outer and inner surfaces respectively complementary to said collar inner surface and to said shank enlargement and flange, said flange forming thereby an axial location means for the arms, at least one key in the outer surface of each arm being engageable by respective complementary slots in the collar inner surface providing thereby circumferential location means for the arms, the maximum dimension of said shank enlargement lying within the length of the collar lower portion.

8. A rotary drill bit assembly comprising, in combination, a hollow shaft, a connection threaded to receive a connector piece at one end, of the shaft for attaching the assembly to a drilling rig and an enlargement at the other end of said shaft, a tubular member concentric with and surrounding the hollow shaft consisting of integrally formed collar and sleeve parts extending axially from each other, the collar'part being concentric with and surrounding said enlargement, drill bit arms held between the collar and the enlargement, the sleeve part surrounding an intermediate portion of the shaft and peripheral engagement means between the sleeve part and the shaft, said collar part having .an outer surface carrying radially projecting side reaming cutters and an inner surface comprising a main frusto-conical portion and radially directed elements adjacent to an outer end thereof circumferentially spaced on said inner surface, the arms having outer peripheral portions closelyfittingisaid frusto-conical portion and elements on said arm outer portions engaging said collar elements, said engagement maintaining the relative circumferential position of said bit arms to said 5 collar, said collar main portion providing, with the enlarged end of the shaft, a frictional coupling for the bit arms, the connector abutting the tubular member to urge it downwardly and so lock the assembly in position.

9. A rotary drill bit assembly comprising, in combination, a hollow shank having a threaded connection at an upper end, a connector piece serewable thereto for attachment of the assembly to a drill stem, at bulbous enlargement at the lower end of the shank, side reaming cutters, a collar surrounding the shank comprising upper and lower portions,'the lower portion, within the axial length of which the maximum radial dimension of the shank enlargement lies, having an inner peripheral surface of downwardly widening frusto-conical form and an outer peripheral surface from which the side reaming cutters project outwardly, the upper portion being located intermediate the length of the shank and rotary driving connection means being provided between the upper portion and the shank, a circumferential flange on said shank between the enlargement and the driving means, two similar detachable bit arms frictionally securable between the shank and the collar lower portion said arms having upper regions with inner and outer surfaces that are, respectively, complementary to said collar lower portion inner surface and to said shank enlargement and flange, said flange forming thereby an axial location means for the arms, at least one key on the outer surface of each arm upper region being engageable by respective complementary slots in the collar lower portion inner surface providing thereby circumferential location means for the arms.

References Cited by the Examiner UNITED STATES PATENTS 2,599,854 6/52 McMurdy et a1 175-413 2,656,153 10/53 White 175-412 2,831,657 4/58 Hawthorne 175-412 2,859,942 11/58 Hawthorne 175-412 2,890,020 6/ 59 Hawthorne et al 175-412 3,039,548 6/62 Briggs 175-412 CHARLES E. OCONNELL, Primary Examiner.

BENJAMIN BENDETT, Examiner. 

1. A ROTARY DRILL BIT ASSEMBLY COMPRISING IN COMBINATION, A HOLLOW SHAFT HAVING AN ENLARGEMENT AT ITS LOWER END AND A THREADED CONNECTION AT ITS UPPER END, A CONNECTOR PIECE ATTACHED TO SAID THREADED CONNECTION, SAID SHAFT CARRYING AXIALLY DIRECTED ELEMENTS INTERMEDIATE SAID ENDS, A COLLAR SURROUNDING THE SHAFT, AN UPPER REGION OF THE COLLAR HAVING ELEMENTS COMPLEMENTARY TO SAID SHAFT ELEMENTS AND FORMING THEREWITH PERIPHERAL ENGAGEMENT MEANS PREVENTING RELATIVE ROTATION BETWEEN THE COLLAR AND THE SHAFT, A LOWER REGION OF THE COLLAR HAVING A FRUSTOCONICAL INNER SURFACE WIDENING TOWARDS THE COLLAR LOWER END AND RADIALLY DIRECTED ELEMENTS ADJACENT TO SAID END CIRCUMFERENTIALLY SPACED ON SAID SURFACE, DRILL BIT ARMS 